Mushoku Tensei: Isekai Ittara Honki Dasu

The story follows a 34-year-old man who is killed after trying to save someone from getting hit by a car. He soon finds himself reincarnated in a magical world as Rudeus Greyrat, except that he gets his whole life reset, starting as a baby.

With all of his knowledge from his previous life, and a new heaping helping of magical ability, Rudeus quickly becomes a formidable warrior ready for adventure. Oh, and he's still a total pervert.